1. Field of the Invention
This invention relates to a ball assembly for use in arranging solder balls or other types of balls in a prescribed pattern in preparation for forming the balls into solder bumps. It also relates to a method for manufacturing a ball assembly, and to a method of forming solder bumps using the ball assembly.
2. Description of the Related Art
One method of soldering an electronic part to a substrate employs solder bumps, which are previously formed on the electrodes of the electronic part and/or the electrodes of the substrate.
Various methods have been proposed in the past for forming solder bumps, such as the solder paste method, the solder ball method, and the plating method. Each of these methods has its advantages and disadvantages. The solder ball method is advantageous in that the amount of solder which is applied to an electrode can be accurately controlled, and it is relatively economical. In carrying out the solder ball method, it is important to accurately position the solder balls on prescribed electrodes.
There have been various proposals for methods of arranging solder balls on electrodes. For example, Japanese Published Unexamined Patent Application Hei 08-115916 and Japanese Published Unexamined Patent Application Hei 10-275974 disclose methods in which solder balls are held in a prescribed pattern by a suction jig, and the solder balls are then transferred by the jig to atop electrodes on a substrate. However, the equipment required for these methods is complicated in structure, and each time the pattern of the electrodes on which the solder balls are to be mounted is modified, it is necessary to remanufacture the jig, which requires the expenditure of considerable amounts of money and time. Furthermore, there is a limit to the electrode pitch which can be achieved by such methods, so they are inappropriate for forming solder bumps on an electrode pattern with an extremely fine pitch.